diff mbox series

[v2,3/8] lib: sbi_hart: reset hstatus

Message ID 20250429142549.3673976-5-rkrcmar@ventanamicro.com
State New
Headers show
Series Reset more security-related CSRs | expand

Commit Message

Radim Krčmář April 29, 2025, 2:25 p.m. UTC 
hstatus.HU must be cleared, because U-mode could otherwise use the
HLS/HSV instructions.  This would allow U-mode to read physical memory
directly if vgatp and vsatp was 0.

The remaining fields don't seem like a security vulnerability now, but
clearing the whole CSR is not an issue, so do that be safe.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
---
v2: Add Reviewed-by [Anup]
---
 lib/sbi/sbi_hart.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 26d746d31dfd..5ea7328a18c9 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -85,6 +85,9 @@  static void mstatus_init(struct sbi_scratch *scratch)
 #endif
 	}
 
+	if (misa_extension('H'))
+		csr_write(CSR_HSTATUS, 0);
+
 	if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMSTATEEN)) {
 		mstateen_val = csr_read64(CSR_MSTATEEN0);
 		mstateen_val |= SMSTATEEN_STATEN;